Yes I have seen this before, molly should be just fine. It will take time to grow out but in the long run it will not hurt her. I looks to be a where an abscess came out. You will hit a point where her heel will almost "fall off" but there will be new good heel by the time you get there. Just make sure she get good farrier work on a regular bases.
Equus717 Thanks it has been fun so far.